With the progress of science and technology, fluctuation of a core voltage (Vcore) of a microprocessor (or called central processing unit) may affect the normal work of the microprocessor. If the core voltage is too high, the microprocessor may generate more heat, have shortened lifespan, and even may be damaged. If the core voltage is too low, data may be corrupted, the computer may be down, and blue screen of death may be generated. Since the density of integration of the core voltage of the microprocessor increases continuously, manufacture craft becomes finer, and the core voltage of the microprocessor is higher and higher, power supply system with higher standard is needed.
In the early days, in a motherboard, the voltage of the microprocessor is set by a jump wire or a dual inline package (DIP) switch. When a microprocessor is assembled or replaced, a user has to plug and pull the jump wire or push the DIP switch on the motherboard to set the core voltage according to the core voltage of the microprocessor in light of a specification of the microprocessor. If the user is careless, the microprocessor and the motherboard may be burned, and this is dangerous. To solve the problem, the Intel company begins to adopt the voltage identification (VID) technique from the Pentium. The VID technique is an adaptive voltage scaling (AVS) technique, and by using the technique, the power supply voltage may be set automatically by the power supply circuit of the motherboard according to the requirement of a CPU, and the user does not need to operate it.
After that, the Intel sets a corresponding voltage regulation model (VRM) standard for each type of processor product. From the Prescott core microprocessor, the voltage regulation standard is named by a voltage regulation down (VRD), the number of the VID digits, a voltage regulation precision and a voltage regulation range in different versions of the voltage regulation standard are different, and the voltage identification code and the number corresponding to the special command such as the “OFF command” in each version of the voltage regulation standard are different. When the voltage identification code is converted using a digital circuit, the voltage identification code corresponding to the special command needs to be avoided. Thus, the voltage identification code before and after a converting process and processor products supporting the voltage regulation standard are compatible.